A Facile Top‐Down Protocol for Postsynthesis Modification of Hierarchical Aluminum‐Rich MFI Zeolites. Issue 3 (14th November 2014)

• Record Type: Journal Article
• Authors: Yu, Lili; Huang, Shengjun; Miao, Shu; Chen, Fucun; Zhang, Shuang; Liu, Zhenni; Xie, Sujuan; Xu, Longya
• Is Part Of: Chemistry. Volume 21:Issue 3(2015)
• Page Start: 1048
• Page End: 1054
• Publication Date: 2014-11-14
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201404817
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>High aluminum content constitutes a major hurdle for the postsynthesis modification of hierarchical zeolites. A facile protocol comprising fluorination and sequential alkaline treatment is presented for the postsynthesis modification of hierarchical Al‐rich MFI zeolites. By virtue of this protocol, uniform intracrystalline mesoporosity is introduced in an Al‐rich MFI zeolite (Si/Al=14.3). The obtained hierarchical zeolites exhibit a significant mesopore size distribution, centered around 6 nm, and show improved conversions in catalytic cracking of bulky aromatic molecules. The fundamental implications of the fluorination–alkaline treatment protocol are related to the formation of F‐bearing tetrahedral aluminum species in the antecedent fluorination step, which alleviates the resistance of Al sites to the alkaline medium and causes AlF complexation for regulated hydrolysis of the Al species during the alkaline treatment process. This top‐down protocol and the derived mechanistic understandings are expected to be applied in the synthesis of hierarchical Al‐rich zeolites with other framework topologies.</p> </abstract>